Cognitive Dissonance is the feeling of uncomfortable tension that arises when holding two conflicting thoughts in the mind at the same time. For the most part we don't like stuff that hurts our brain. So naturally we avoid stuff that hurts our brain. This leads, at least in part, to the observation that conservatives favor conservative blogs and that liberals favor liberal blogs. For the most part there is not much overlap.
Now a couple of economists have done an analysis of bias in the media. From the NYT Economic Scene:
As Dr. Shapiro put it in an interview, “The data suggest that
newspapers are targeting their political slant to their customers’
demand and choosing the amount of slant that will maximize their sales.”
...
So although politicians from both sides tend to accuse the news media
of partisanship and negativity, the data suggests that they ought to
blame the public. The papers basically reflect what their readers want
to hear [emphasis added].
The NYT article is based on a new study by Jesse Shapiro and Matthew Gentzkow. Here's the NBER version (gated) and a working paper (free). This is a follow-up to Shapiro and Gentzkow's earlier paper on media bias. From the abstract:
[A] consumer who is uncertain about the quality of an information source will infer that the source is of higher quality when its reports conform to the consumer’s prior expectations.
The paper is available on Shapiro's page, linked above.
